Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue recognized	$ 3,000	$ 0	$ 0
Operating Expenses [Abstract]
Research and development	41,932	30,163	20,346
General and administrative	20,942	17,640	8,739
Loss on transfer of nonfinancial assets	0	3,900	0
Total operating expenses	62,874	51,703	29,085
Loss from operations	(59,874)	(51,703)	(29,085)
Nonoperating Income (Expense) [Abstract]
Interest income	273	1,197	236
Interest expense	(2,688)	(2,147)	(720)
Change in fair value of preferred stock warrant liability	0	(288)	(3,398)
Change in fair value of derivative liability	(437)	183	(89)
Loss on extinguishment of debt	(162)	(566)	(229)
Other income	905	517	0
Total other expense, net	(2,109)	(1,104)	(4,200)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(61,983)	(52,807)	(33,285)
Income Tax Expense (Benefit)	148	0	0
Net loss	(62,131)	(52,807)	(33,285)
Accruing dividends on Series A convertible preferred stock	0	(592)	(3,000)
Adjustment to accumulated deficit in connection with repurchase of Series Seed convertible preferred stock	0	0	(22)
Net loss attributable to common stockholders	$ (62,131)	$ (53,399)	$ (36,307)
Net loss per share attributable to common stockholders - basic and diluted (in dollars per share)	$ (3.09)	$ (4.63)	$ (79.15)
Weighted average shares of common stock outstanding - basic and diluted (in shares)	20,077	11,530	459
Currency translation adjustments	$ 0	$ (119)	$ 0
Total comprehensive loss	$ (62,131)	$ (52,926)	$ (33,285)